* Add `overlays` property to `MGLMapView.mm`
Implemented by filtering the `annotations` property for
annotations that conform to `MGLOverlay` protocol.
* Handle `nil` case when returning overlays
* Add basic documentation for `overlays` property
Copied verbatim from `annotations` property. Changed types.
* Add `overlays` property to iOS sdk
Implementation is identical to the one in macOS SDK.
* Match curly braces style
* Make `overlays` property `nonnull` on iOS
* Make `overlays` property `nonnull` on macOS
* Make cosmetic changes
* [ios, macos] Moved changelog entry to master
9e6a79ad9b